In an image formation process of a silver halide photographic light-sensitive material, it is recently desired to reduce the processing time. However, if the time is reduced, there is not given sufficient time for completing decoloration of unnecessary dyes (which are required in the exposure step), sensitizing dyes or de-sensitizing dyes contained in the light-sensitive material, or removing those dyes from the light-sensitive material. Therefore, the obtgained image unfavorably has a residual color derived from those dyes.
In order to solve these problems, there has been proposed a method of employing water-soluble dyes to increase the decoloring efficiency. Further, a solution for processing for the decoloring have been studied to increase the decoloring efficiency. For example, there are known as methods of reducing the residual color: (1) a method of adding a water-soluble stilbene compound; a nonionic surface active agent or a mixture thereof to a developing solution, (2) a method of treating the photographic material with an oxidizing agent after bleaching and fixing to rupture the dye, and (3) a method of using a persulfuric acid-bleaching bath as a bleaching bath, as described in "Research Disclosure", Vol. 207, No. 20733 (July, 1981). However, in these methods, satisfactory decoloration can not be attained when the color remains at high density. Further, according to these methods, detachment and removal of the dyes such as sensitizing dye is no accelerated. Hence, these methods are unsuitable for rapid decoloration.
Decoloring methods of dyes are also described, for example, in Japanese Patent Provisional Publications No. 64(1989)-4739, No. 64(1989)-15734, No. 1(1989)-9451, No. 64(1989)-35440, No. 1(1989)-21444, No. 1(1989)-35441 and No. 1(1989)-159645. Any of these methods comprise incorporation of an additive to a developing solution or other processing solution. These methods also are insufficient, although they improve decoloring efficiency to some extent. Further, as a similar method, a method of decoloring by rupturing association of sensitizing dyes is proposed in U.S. Pat. No. 4,906,553 and Japanese Patent Provisional Publication No. 2(1990)-71260. This method comprises incorporation of an additive to a processing solution, so as to give decoloration at high efficiency. Particularly, the method described in Japanese Patent Provisional Publication No. 2(1990)-71260 is excellent in decoloring. However, since the activity of the processing solution for decoloration decreases with the elapse of time or after repeated use of the processing solution, the processing solution should be stored under severe control.
As described previously, there are known the use of water-soluble sensitizing dyes to reduce residual color in the resulting image. Howerver, these sensitizing dyes have disadvantages; for example, the spectral sensitivity is low or the level of the residual color is not sufficiently low (see: U.S. Pat. No. 4,250,224). Japanese Patent Provisional Publication No. 3(1991)-105339 discloses a thiazole type sensitizing dye which gives reduced residual color and showing high spectral sensitivity. However, this thiazole type dye is not still sufficiently improved in giving the residual color when the material containing the dye is processed by a photographic process including a conventional developing step, though the spectral sensitivity of the dye is high.
As described above, in order to decolor unnecessary dyes in the process for forming an image such as a photographic image, these dyes are generally removed from the photographic material after the exposure step. However, the decoloraion process for efficiently removing the unnecessary dyes is complicated, and this complicated process disturbs reduction of the processing time of a photographic light-sensitive material in the developing process. Studies on the sensitizing dyes which are easily removed in the generally employed developing process have been also made, but no sensitizing dyes which are satisfactory in both the spectral sensitivity and the level of the residual color have been discovered.
Recently, small sized development processing devices (so-called "mini-laboratory") have been widely employed, and hence it is desired to carry out the decoloration in a manner as simple as possible and within a short time. Further, a system or a dye which needs no decoloration processing is desired, from the viewpoints of reduction of waste processing solutions and prevention of environmental pollution.